Research article
Evolutionary history of the endangered fish Zoogoneticus quitzeoensis (Bean, 1898) (Cyprinodontiformes: Goodeidae) using a sequential approach to phylogeography based on mitochondrial and nuclear DNA data
1 Posgrado en Ciencias del Mar y Limnología, ICMyL, Universidad Nacional Autónoma de México, C. P. 04510, D. F. México, México
2 Laboratorio de Biología Acuática, Facultad de Biología, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México
3 Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal, 2, 28006 Madrid, España.
4 Instituto de Biología, Universidad Nacional Autónoma de México, Ap. Postal 70-153. C.P. 04510 México D.F., México.
BMC Evolutionary Biology 2008, 8:161 doi:10.1186/1471-2148-8-161
Published: 26 May 2008Abstract
Background
Tectonic, volcanic and climatic events that produce changes in hydrographic systems are the main causes of diversification and speciation of freshwater fishes. Elucidate the evolutionary history of freshwater fishes permits to infer theories on the biotic and geological evolution of a region, which can further be applied to understand processes of population divergence, speciation and for conservation purposes. The freshwater ecosystems in Central Mexico are characterized by their genesis dynamism, destruction, and compartmentalization induced by intense geologic activity and climatic changes since the early Miocene. The endangered goodeid Zoogoneticus quitzeoensis is widely distributed across Central México, thus making it a good model for phylogeographic analyses in this area.
Results
We addressed the phylogeography, evolutionary history and genetic structure of populations
of Z. quitzeoensis through a sequential approach, based on both microsatellite and mitochondrial cytochrome
b sequences. Most haplotypes were private to particular locations. All the populations
analysed showed a remarkable number of haplotypes. The level of gene diversity within
populations was 
d = 0.987 (0.714 – 1.00). However, in general the nucleotide diversity was low, π =
0.0173 (0.0015 – 0.0049). Significant genetic structure was found among populations
at the mitochondrial and nuclear level (ΦST = 0.836 and FST = 0.262, respectively). We distinguished two well-defined mitochondrial lineages that
were separated ca. 3.3 million years ago (Mya). The time since expansion was ca. 1.5 × 106 years ago for Lineage I and ca. 860,000 years ago for Lineage II. Also, genetic patterns of differentiation, between
and within lineages, are described at different historical timescales.
Conclusion
Our mtDNA data indicates that the evolution of the different genetic groups is more related to ancient geological and climatic events (Middle Pliocene, ca. 3.3 Mya) than to the current hydrographic configuration of the basins. In general, mitochondrial and nuclear data supported the same relationships between populations, with the exception of some reduced populations in highly polluted basins (Lower Lerma River), where the effects of genetic drift are suggested by the different analyses at the nuclear and mitochondrial level. Further, our findings are of special interest for the conservation of this endangered species.
